HKS Stainless Front Pipe for 2008-14 Subaru WRX [GRB] 33006-BF003


HKS Legamax Exhaust; Includes Center Pipe; For use with HKS Bellmouth Downpipe #33006-BF003 by HKS for the Subaru WRX STI

HKS PN# 31008-BF001

Please note that this brand offers a wide variety of parts, some of which are kept in stock. However, not all products from this brand are kept in regular inventory. As a result, lead times can vary (from 1 day to weeks or months). Following your order, a representative will contact you to explain the order process, and provide an estimated timeframe for delivery. . Following the discussion, should you choose to continue with the order there will be no further option for cancellation (if there are any concerns regarding lead time, please advise us immediately during the initial follow-up). Please order with confidence, as at the time of the initial contact and after being informed of the estimated lead time, should you choose to cancel, you may do so within 1 business day. You are encouraged to read and understand the full terms and conditions of the sale here.


This product is designed and manufactured specifically for the Subaru WRX STI. This product includes the center pipe and is for use with the HKS bellmouth downpipe.



Reduction of secondary exhaust gas back pressure will improve response of turbocharger.
EJ engines’ common problem of knocking due to high exhaust gas pressure can be solved. Thus, it is recommended for safe performance upgrading.

  • It was developed based on long time know-how of turbo technology.
  • The connection portion with turbine is made by lost wax casting that enables flat surface between flange and pipe.
  • Improved exhaust efficiency without catalytic converter. (Off-road use only)
  • For improvement of exhaust efficiency, diameter of the pipe is Φ75.
    If it is used with the specified muffler (31008-BF001)(*), whole exhaust system will be Φ75.
    * Front Pipe and Muffler system set (31008-BF002) is available.
    (This item can be used with other exhaust systems. A Flange Adaptor is included to fit to Φ65 spherical flange.)


Whole front pipe will be changed from stock Φ60 to Φ75. It reduces secondary exhaust gas back pressure that is a common problem of EJ engines.

Φ75 flange. With the specified muffler, whole exhaust system will be Φ75.

Extension flange portion has smooth surface by lost wax casting.

Extension portion has HKS logo.



BB Tune

BB Tune is…
“Boxer’s Balance Tune” and it is a project of HKS to analyze completely about typical problems of EJ20 engine due to its boxer engine layout. Previously, EJ20 engine had been considered as it was easy to be damaged. To find out the cause, the engine was analyzed on test bench at HKS and found out that reducing back pressure is the point to prevent knocking and the know-how changed EJ tuning in Japan. Since EJ25 has the same engine layout, reducing back pressure is effective for safe tuning.
To reduce secondary back pressure, replacement of front pipe will be required for further tuning.

If interested, please contact us at Bulletproof Automotive for more information regarding pricing, fitment, shipping costs, as well as installation recommendations.

Part #: 31008-BF001